machine_desc

Each machine must define its own machine_desc structure, which defines some of the most basic characteristics of the machine.

struct machine_desc {

unsigned int nr; /* architecture number */

const char *name; /* architecture name */

unsigned long boot_params; /* tagged list */

const char **dt_compat; /* array of device tree

* 'compatible' strings */

unsigned int nr_irqs; /* number of IRQs */

unsigned int video_start; /* start of video RAM */

unsigned int video_end; /* end of video RAM */

unsigned int reserve_lp0 :1; /* never has lp0 */

unsigned int reserve_lp1 :1; /* never has lp1 */

unsigned int reserve_lp2 :1; /* never has lp2 */

unsigned int soft_reboot :1; /* soft reboot */

void (*fixup)(struct machine_desc *,

struct tag *, char **,

struct meminfo *);

void (*reserve)(void);/* reserve mem blocks */

void (*map_io)(void);/* IO mapping function */

void (*init_early)(void);

void (*init_irq)(void);

struct sys_timer *timer; /* system tick timer */

void (*init_machine)(void);

};

In arch/arm/include/asm/mach/arch.h, there is the following macro, which is used to declare the processor-related machine_desc structure and put the structure into the segment specified in vmlinux.lds.

#define MACHINE_START(_type,_name)

static const struct machine_desc __mach_desc_##_type

__used

__attribute__((__section__(".arch.info.init"))) = {

.nr = MACH_TYPE_##_type,

.name = _name,

#define MACHINE_END

};

Use the above macro to declare the machine_desc structure in arch/arm/mach-s3c64xx/mach-smdk6410.c.

MACHINE_START(SMDK6410, "SMDK6410")

/* Maintainer: Ben Dooks */

//.phys_io = S3C_PA_UART & 0xfff00000,

//.io_pg_offst = (((u32)S3C_VA_UART) >> 18) & 0xfffc,

.boot_params = S3C64XX_PA_SDRAM + 0x100,

.init_irq = s3c6410_init_irq,

.map_io = smdk6410_map_io,

.init_machine = smdk6410_machine_init,

.timer = &s3c24xx_timer,

MACHINE_END

The above macro expands to:

static const struct machine_desc __mach_desc_SMDK6410 __used __attribute__((__section__(".arch.info.init"))) = {

.nr = MACH_TYPE_SMDK6410,

.name = "SMDK6410",

.boot_params = S3C64XX_PA_SDRAM + 0x100, //0x5000_0100

.init_irq = s3c6410_init_irq,

.map_io = smdk6410_map_io,

.init_machine = smdk6410_machine_init,

.timer = &s3c24xx_timer,

}

MACH_TYPE_SMDK6410 is defined in the arch/arm/tools/mach-types file

# machine_is_xxx CONFIG_xxxx MACH_TYPE_xxx number

1621: smdk6410 MACH_SMDK6410 SMDK6410 1626